C Error Parent does not contain a constructor that takes 0 arguments

Question

My code is  public class Parent        public Parent int i                Console WriteLine  parent             public class Child   Parent       public Child int i                Console WriteLine  child               I am getting the error      Parent does not contain a constructor that takes 0 arguments    I understand the problem is that Parent has no constructor with 0 arguments  But my question is  why do we need a constructor with zero arguments  Why doesn t the code work without it

User · Answer

By default compiler tries to call parameterless constructor of base class.

In case if the base class doesn't have a parameterless constructor, you have to explicitly call it yourself:

public child(int i) : base(i){
Console.WriteLine("child");}

Ref : Constructor calling hierarchy during inheritance

User · Answer

Since you don t explicitly invoke a parent constructor as part of your child class constructor  there is an implicit call to a parameterless parent constructor inserted  That constructor does not exist  and so you get that error   To correct the situation  you need to add an explicit call   public Child int i    base i        Console WriteLine  child        Or  you can just add a parameterless parent constructor   protected Parent

User · Answer

You need to change your child s constructor to   public child int i    base i           etc        You were getting the error because your parent class s constructor takes a parameter but you are not passing that parameter from the child to the parent    Constructors are not inherited in C   you have to chain them manually

User · Answer

You need to change the constructor of the child class to this   public child int i    base i        Console WriteLine  child        The part   base i  means that the constructor of the base class with one int parameter should be used  If this is missing  you are implicitly telling the compiler to use the default constructor without parameters  Because no such constructor exists in the base class it is giving you this error

User · Answer

The compiler cannot guess what should be passed for the base constructor argument   You have to do it explicitly   public class child   parent       public child int i    base i            Console WriteLine  child

User · Answer

You can use a constructor with no parameters in your Parent class     public parent

[c#] C# Error: Parent does not contain a constructor that takes 0 arguments

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